Purging arrangements for absorption refrigeration systems



June 14, 1960 w. 1 MOGRATH 2,940,274

PURGING ARRANGEMENTS FOR ABSORPTION REFRIGERATION SYSTEMS Filed March 16, 1956 2 Sheets-Sheet 1 INVENTOR.

F I I WILLIAM L. MCGRATH.

w SM ATTORNEY.

June 14, 1960 w. 1.. M GRATH 2,940,274

PURGING ARRANGEMENTS FOR ABSORPTION REFRIGERATION SYSTEMS Filed March 16, 1956 2 Sheets-Sheet 2 FIG. 2

IN V EN TOR.

WILLIAM L. MCGRATH.

BY W. SM

ATTORNEY.

United States Patent PURGING ARRANGEMENTS FOR ABSORPTION REFRIGERATION SYSTEMS William L. McGrath, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Mar. 16, 1956, Ser. No. 571,967

Claims. (Cl. 6H5) condenser of the absorption refrigeration system. This mechanism is satisfactory in use but is somewhat expensive in initial cost and operating costs and requires considerable maintenance in use. The mechanism operates continuously so that over a period of time small quantities of refrigerant and absorbent are withdrawn from the system and discharged to waste with the non-condensible gases, steam condensate and water employed to actuate the Water ejector.

The chief object of the present invention is to provide a purging arrangement for an absorption refrigeration V system which obviates the disadvantages inherent in prior arrangements.

An object of the invention is to provide a purging arrangement for absorption refrigeration systems which returns refrigerant withdrawn from the refrigeration system to the system, thus eliminating the necessity of additional refrigerant and/or absorbent being added to the system during long continuous periods of operation.

A further object is to provide a purging arrangement for an absorption refrigeration system employing an absorbent solution substantially the same as the absorbent solution employed in the refrigeration system which is capable of withdrawing non-condensible gases and reclaiming and returning the refrigerant to the refrigeration system without interference with the operation of the refrigeration system.

A still further object is to provide a purging arrange ment for an absorption refrigeration system which is eifective to withdraw non-condensible gases and to return automatically excess absorbent solution to the refn'geration system, thus eliminating waste and ineflicient operation of the refrigeration system. Other objects of the invention will be readily perceived from the following description.

This invention relates to a purging arrangement for an absorption refrigeration system comprising, in combination, a container, a pivot member supporting the container in a first position, said container tilting upon the pivot member to a second position when a desired level of solution in the container is attained, a pump for circulating solution in the container, an ejector connected to the pump having a nozzle opening, a line adapted to connect the ejector with the absorber of the refrigeration system whereby discharge of solution through the ejector by said pump induces non-condensible gases from the absorber and forwards the non-condensible gases to the container for discharge to ambient atmosphere, means for controlling the operation of the pump, tilting of the container actuating said means to discontinue operation of the pump whereby atmospheric pressure forces solution in the tank through said line to the absorber until a desired level of solution in the container is attained permitting the container to return to its first position thus permitting said means to resume operation of the pump.

This invention further relates to a method of purging an absorption refrigeration system including an absorber, an evaporator, a generator and a condenser in which the steps consist in circulating solution in a container to induce non-condensible gases from the absorber and, when the volume of solution in the container increases to a desired level, tilting the container to discontinue operation of circulation means thereby discontinuing circulation of solution in the container and withdrawal of non-condensible gases from the absorber, supplying solution in the container to the absorber, and, when the volume of solution in the container has decreased to a desired level, returning the container to its first position to resume operation of the circulation means thereby again circulating solution in the container and withdrawing non-condensible gases from the absorber.

The attached drawings illustrate a preferred embodiment of the invention, in which Figure 1 is a diagrammatic view of an absorption refrigeration system including the purging arrangement of the present invention; and

Figure 2 is a sectional view of the purging arrangement.

Referring to the attached drawings, there is illustrated in Figures 1 and 2 the purging arrangement of the present invention employed in an absorption refrigeration system of the type disclosed and claimed in the ,co-pending application of Louis H. Leonard, Serial No. 505,369, filed May 2, 1955, now Patent No. 2,840,997, entitled Absorption Refrigeration Systems. Referring specifically to Figure 1, the absorption refrigeration system comprises a shell 2 containing a plurality of tubes 3 which cooperate with the shell to form an absorber. Placed in shell 2 above absorber 3 is a pan-like member 4 which cooperates with shell 2 to form an evaporator.

A second shell 5, preferably, is placed above the first shell. Tubes 6 extend in the lower portion of shell 5 I and cooperate with shell 5 to form a generator or boiler.

A plurality of tubes 7 are placed in the upper portion of shells which cooperate with a pan-like member 8 to form a condenser.

A double pump arrangement is provided to circulate solution through the system. This arrangement includes pump 9 which serves to supply weak solution from the absorber to the generator and pump 10 which serves as an absorber pump. Pumps 9 and 19 are driven by a motor 11. If desired, separate motors may be provided.

Pump 9 withdraws Weak solution from absorber 3 through outlet or sump 12 and line 13. Pump 9 forwards the weak solution through line 14, heat exchanger 15 and line 16 to generator 6. Strong solution is drawn from generator 6 through line 17 to an overflow arrangement 18 which maintains a desired level of solution in generator 6 and is returned to the absorber through line 19, heat exchanger 15, line 20 and inlet 21 of absorber 3 by forces of gravity. Strong solution may be dumped 6 'fthroughf sateensolution mixes to some extent with solutionin'the' ab-'" It is important that this Vapor v, p

be liberated in a man'ner that does not interfere with the collection ci'non-condensible gassat'a specific location beneaththe tubes. V

Pump 33supplies condensingwater through line '31 to the tubes 3 of the absorber. The condensing water after 7 tubes 7 of the condenser. The condensing water after passage through the tubes of the condenser is discharged to a cooling tower or drain through line 33. If desired a by-pass line 34 is provided about tubes 7 of the 'condenser, extending from line 32 to line 33.

a passage through tubes 3 passes through line 32 to the Chilled water is withdrawn from the evaporator 4 through line 35 by pump 36 and is circulated to a place of use which may be the central station of an air conditioning system through line37. The chflled Water is returned to the evaporator through line 38' and is flashcooled in the evaporator the flashed vapor'passing to the "absorber;

Condensate leaves condenser 7 through line 39 and is returned to the "evaporator, being flash-cooled in the evaporator, the flashed vapor passing to the absorber, as previously described. A tank or container 40 is placed in line 39, for a purpose hereinafter described.

The purging arrangement 41 of the present invention 4 fiecting the load imposed upon'the system. Branch line 53 is connected to valve 50 by line 60. Thermostats 52 and 54 regulate the air pressiire supplied to the diaphragm of valve 50.

A rotary switch 61 is provided which is connected to a mercury switch 62. Mercury switch 62 may be actuated 'by means ofa bellows'and a bulb63 placed adjacent chilled waterline 35 and reflecting 'the teuiperature of chilled water therein. Mercury switch 62 serves in efiect as a safety control. Anjint zrease in temperature of chilled water above a predetermined point opens this switch thereby closing valve 58 to prevent supply of air to controls 52, 54 and valve59. The starters "64-a'n'd 65 actuate the motcr llof .pumps 9, 1i) and the motor (not 7 shown) of chilledwater pump 36. The starter for the condensing water pump 30 is not shown since such pump and motor are generally provided by the installer.

1 The control arrangement shown herein is disclosed in the patent to Louis H. Leonard, No. 2,722,805, issued November 8, 1955, entitled Control Arrangement for Absorption Refrigeration System, and reference is made to such patent'for a full description of the control arrangement and the manner in which it operates.

The term weak solution is used herein to describe a solution weak in absorbing power. The term strong solution is used herein to define a solution strong in absorbing power;

A preferred absorbing sblutionis a solution of lithium bromide, in water; the preferred refrigerant is water. With such solution preferably, the solution concentration leaving the generator is 66%. A greater concentration may permit crystallization to occur, causing solidification in the heat, exchanger and, perhaps, in other portions of the system.

' The purging arrangement 41 is shown in Figures 1 and 2. Referring to Figures 1 and '2 there is shown a conislprovided to remove non-conden'sible gases from the system. This purging arrangement" will be more fully described hereinafter. A purge line 42 extends gener ally longitudinally of the absorber below the tube bundle, preferably, at the center of thebu'ndle.

Steam is supplied to the tubes 6 placed in line 45 to assure desired steam pressure in the generator. Valve '46 assures that pressure of steam passifig to the generators .co'ntrolled at a predetermined point. steam ondensate leaves the tubes'of generator '47, astea'm trap 48' beingp'laced in line '47 to asmrettaronly condensate leaves the generat r;

A nonnauy clos'ed'paeuniatic valve 50'isplacedinline 33 between the tubes 7 of, the condenser and the connection of by-pa'ss, line 34- with'line 33. Valve 50 regulates of the generator [t l1frough line 45. A pressure "regulating valve 46 may be phssa'ge of 'cbiideiis'ing water through the tubes offcondenser 7. By-pass 34 assures that fi'ow of condensing water is maintained substantially constant while permitting variation in the flow of condensing water through the tubes of condenser 7.

A thermostatic control 52 regulates the pressure of airpassing through branch line 53 to a second thermostatic control54. Thermostaticcontrol 54 in turn regulate the air pressure applied to valve 50. Control 52 is'a'ctuated byin'eans of a bulb 55 placed adjacent chilled waterline 35. 3111555 re'flect's ftheftemperat'ure' of chilledfviater which injturn indicates the was im osed upon the systern. cohtroledis actuated by bulb 5 6pla'cefdi1in eon: tainer 4o ra ns 59. and reflects saturation "temperature corresponding to pressnre'in shell 5.- I

Compressed "air is supplied to the controls main air line 57. Preferably a solenoid valve 58 or relay of suitable. design is placed therein as a safety cbntrol;

Airpress'ure passes from line 57 to line 53. Thermostat 5 2 is connected to line 53 by branch line 59'; thusjprefssure inbranch line53 maybe regulated by thermostat 52 bleeding aportionof air therein to the atrnb'sphe f tenants with the temperature bf the trainee a.

" sulfa e switbhhfimlier tainer ortanli 79 adapted to contain a solution of absorbent and refrigerant similar to the absorbent and refr'igerantemployed in the absorption refrigeration system. Preferably, the, container is thermal and sound insulated. 'The solution employed in the present purging arrange- "ment comprises a solution of lithium bromide and water similar to the absorbent and refrigerant employed in the absorbentrefrigeration system with which the purging arrangementis used. ,It will be understood, of course, other solutions of absorbent and refrigerant may be'used spending upon the absorbent and refrigerant employed in refrigeration system. V I g V J Thecontainer has one'side indicated at 71 extendirig'outwardlyat an angleso that the top of the container "is of greater length or has" a greater area than thebas'e 72 of the container. The container is mounted onapivot member 73. 'Due to the contourof the container, as the volume ofsolution in the container increases to a predetermined level or volume, the container tilts or pivots on member '73, toward the'left as shown in the figures, to the positionsho wn in dotted outline. Suitable stopmembers 74, 75 are provided to restrain movement of the container beyond a desired point. 7

A"cooling coil 76 is placecl in the container and-is connected to'chilled water line-'37 or the outlet of punip 36 byline 77. I The outlet of coil 76 may beeonnected to, line 78716 ram-a chilled waterto the evaporator are 1s passa e in heat exchange relation 'withsolution container 70. Qthersourc es of cooling water'may be ejin ployedfifi des'; p i A a p 7 9 driven symdtsrso is placed in container 70 r i nn e'cted to ejector 8 1 "also the container to circulatesblution'inthe container. Motor 80is'connected in th ectric'alcircuit of the system. The ejector 8-1 i of 'ejectdr {81*is f th an liness'a shswn as a marshal teat circuit actuating motor 80 of pump 79. When non-condensible gases are being purged from the absorber, switch 85 is in closed position permitting energization of motor 80. An arm 86 carrying a finger 87 is provided adjacent the switch arm 88 of switch 85. A spring 89 holds the arm 86 away from switch arm 88. However, when container 70 is tilted, it contacts arm 86 moving it downward toward switch arm 88 and urging finger 87 in contact with switch arm 88 to move it from one of its contacts thus breaking the electrical circuit and deenergizing motor 80.

Considering the operation of the purging arrangement, lithium bromide solution is discharged by pump 79 through ejector 81 to induce non-condensible gases from the absorber through line 83. A properly designed ejector, of course, will pull a vacuum corresponding to the saturated vapor pressure of the liquid being discharged through it. The solution and non-condensible gases pass from outlet 82 of the ejector into the container where the solution is again circulated by pump 79. The noncondensible gases bubble ofi to atmosphere in the container.

Since cooling coil 76 is supplied with chilled water from the refrigeration system, it possesses a lower vapor pressure than solution circulated in the refrigeration system because it is cooler; thus, the suction pressure of ejector 81 is lower than pressure in the absorber. Since pressure at the suction of ejector 81 is lower than pressure in the absorber, non-condensible gases are withdrawn from the absorber through line 83. Solution in the container absorbs and condenses refrigerant so that the solution separates refrigerant from non-condensible gases. The non-condensible gases are extremely insoluble in lithium bromide thus permitting such separation. The non-condensible gases are released from the surface of solution in the container to the atmosphere.

During the purging process, some amount of water vapor (refrigerant) is gradually removed from the refrigeration system. The refrigerant or water vapor is absorbed and condensed by the solution in the container gradually weakening the solution, increasing its vapor pressure and also increasing the volume of solution in the container. When the volume of solution in the container increases to a predetermined level, container 70 tilts from its first or normal position to a second position, shown in dotted outline in Figure 2. Movement of container 7 0 to a second position brings the container in contact with arm 86 thus urging finger 87 in contact with switch arm 88 to move switch arm 88 from its contact thus deenergizing motor 80 to discontinue operation of pump 79. Under these circumstances, pressure of ambient atmosphere is suificient to force solution in the container through line 83 and purge line 42 to the absorber.

A decrease in the volume of solution in container 70 to a predetermined level permits container 70 to resume again its first or normal position, thereby moving finger 87 away from switch arm 88 to permit the circuit to be closed to energize motor 80 thereby placing pump 79 in operation, as previously described.

As stated above, the solution including the refrigerant is returned to the absorber, mixing with solution therein and being forwarded to the generator. In the generator, refrigerant is boiled ofi, condensed in the condenser and returned to the evaporator.

As shown in Figure 1, preferably, a tube 90 is provided in the absorber to collect a small amount of lithium bromide solution from the absorber spray arrangement 25. This small amount of solution drains through line 91 to the purge line 42 and is withdrawn with non-condensible gases to container 70. The amount of solution provided is not critical since only a minimum amount of solution need be provided.

The present invention provides a simple inexpensive purging arrangement for use with an absorption refrigeration system. It will be understood it may be employed with any desired type of absorption refrigeration system. The refrigeration system is maintained under vacuum during shut-down since the purge valve isolates the system from the purging arrangement thus obviating non-condensible gases seeping into the system during shut-down through the purge line. In the present invention, refrigerant vapor removed from the system is reclaimed and returned to the system.

While I have described certain preferred embodiments of the present invention, it will be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In a purging arrangement for an absorption refrigeration system the combination of a container open to the atmosphere, a pivot member supporting said container in a first position, said container tilting upon said member to a second position when a desired level of solution in the container is attained, a pump for circulating solution in the container, an ejector connected to the pump having a nozzle opening, a line adapted to connect the ejector with the absorber of the system whereby discharge of solution through the ejector by said pump induces noncondensible gases from the absorber and forwards the non-condensible gases to the container for discharge to ambient atmosphere, means for controlling the operation of said pump, tilting of said container actuating said means to discontinue operation of the pump, atmospheric pressure when operation of the pump is discontinued forcing solution in the tank through said line to the absorber until a desired level of solution in the container is attained permitting the container to rem-m to its first position thus permitting said means to resume operation of said pump.

2. In a purging arrangement for an absorption refrigeration system, the combination of a container, a pivot member supporting said container in a first position, said container tilting upon said member to a second position when a desired level of solution in the container is attained, a pump for circulating solution in the container, an ejector placed in said container connected to the pump having a nozzle opening, a line adapted to connect the ejector with the absorber of the system whereby discharge of solution through the ejector by said pump induces noncondensible gases from the absorber and forwards the non-condensible gases to the container for discharge to ambient atmosphere, means for controlling the operation of said pump including a prime mover, a switch and an electrical circuit including the prime mover and the switch, said switch in normal position permitting energization of the prime mover, and means actuated by movement of the container to a second position to open said switch to discontinue operation of prime mover, at least some portion of the solution in said container being forced by atmospheric pressure to return to the absorber through said line when operation of said prime mover is discontinued.

3. A purging arrangement for an absorption refrigeration system according to claim 2 in which the control means include an arm carrying a finger, resilient means retaining said arm in normal position, tilting of the container moving the container in engagement with the arm to move the finger in contact with the switch arm to deenergize the pump.

4. A purging arrangement for an absorption refrigeration system according to claim 3 in which stop members are provided to regulate tilting movement of the container.

5. A purging arrangement for an absorption refrigeration system according to claim 1 in which stop members are provided to regulate tilting of the container.

6. In a method of purging an absorption refrigeration system including an absorber, an evaporator, a generator and a condenser, the steps which consist in circulating solution in a container to induce non-condensible gases from the absorber and when volume of solution in the container increases to a desired level, tilting the container to discontinue operation ofei'reulafion means therehj'; dis-- of solution in the container and ensible gases'from theab'sorber; ofti'c'in 6f the solution in the coneentinningi cire'ulatiofi W t w Slippy 1,

to theabsbr bf when circulation" 'ef-seluti'on' in the ti'on' in" the eeiitaifierli'as decfezisedt a" desire-(1 1ml returning 1 the container to its fir'sft pos n to resume ep'eratio ger thee'iitiulatiomeans there circulating s'llitibii' in "the container and Withdrawing" neneon;

'densiblefgas'e's fieni the anserber. j

container for eirc'ulatingflutd inure container, an ejector in the container connected to thepump for withdrawing non-condensible gases from an area to be'p'u'rged; and means for discontinuing operation ofthepump; said means Being actuated by ti tin -pr the'container;

9. In a'purging" system; theconihination of a container,

7 a pivot mem er supportingthe container in a first posi&

tion, said container tilting upon said'inember to'a second position when a desired lever of fluidinthe container'is attained, a pump for irculating" liquid in the container,

7 an ejector connected to the pump, a line connectingfthe ejector area to he wherehy discharge of liquid through-the ejector by the pump induces non-condensible' gases from the area and forwards the non: condensibl'e gases to the" container for discharge, means" for controlling" operation of the puhigytilting of the container to as'eco'nd position actuating'said means to" discontinuefop'eratzion of the pump the'jreby permitting; fluid in thfecontai'rier to return to sa'id' area through sai'd line, return ofthie "container to its first position permitting said means to resume operation of the pump.

A 10. Ina method tof purging, the stepswhich consist in circulating fluid-in a container to induce non-eondensibie gas-estrom an area to be purged, and, when yolunre-ofiiuid in the container increases to a desired level; tilting-the o'ntainer to discontinue operation of circulation means therebydiscontinuing circulation of fluid in the containerandwithd'rawal of non-condensible gases from the area while supplying at'le'ast some portion of the fluid to the area; and, when volume of fluid in the container has" decreased to a desired level, returning the container to original position to resume purging of the area.-

1 References Cited in the file-of this patent r UNITED STATES PATENTS 2,353,859 Th es hinnin July 18, 1944 2,363,331 Anderson Nov. 21, 1944 2,37%,521; Anderson Apr. 24, 1945 annals Reid 1... May 14, 1946 2,494,972 Thomas Jan. 17, 1950 2,6 1 0 4 8 2 Berry n Sept. 16, 1-952 2,61 9 ,90 6; Gardenhour Dec. 2, 1952 2 802497 Leonard et a1.- -2. Oct. 15, 1957 

